Tuesday, February 24, 2009

Comet Lulin Appears

Comet Lulin (C/2007 N3) is a comet discovered by Quanzhi Ye, a student at Sun Yat Sen Universty from sky photos taken at Taiwan's Lulin Observatory. About 20 hours ago around 0300 ET in the early morning of Feb 24, the comet made its closest approach to Earth at a distance of 0.41 AU.

The comet appears to be a first time visitor to the inner solar system. The NASA Swift Ultraviolet and X-Ray Explorer has been used to get images of the comet at ultraviolet and x-ray wavelengths. The data from Swift shows that it is shedding water at a rate of 3,000 litres per second (enough to fill an Olympic-sized swimming pool in about 15 minutes), and surrounded by a Jupiter-sized cloud of cyanogen and diatomic carbon, glowing green as these compounds fluoresces in sunlight.

Comet Lulin currently has a brightness of visual magnitude +5.5. This level of brightness will drop over time for two reasons - first, due to increasing distance as the comet gets farther away from us. The second reason for a drop in brightness is a change in the amount of light reflected by the comet. As the comet reaches perihelion and starts moving farther from the sun, the amount of material blown off by heat and solar radiation will decrease, and the comet's extended halo and tail will decrease in size resulting in less light being reflected.

At +5.5, Comet Lulin will be difficult to spot in Toronto with the naked eye, although it should be fairly easy to see with binoculars for the next few days. Darker locations away from the middle of a city, like Lake Herridge, or Almonte, or the middle of Saskatchewan will be more ideal.